During loading and unloading of trucks, trailers and other vehicles it is important that the vehicles be secured to prevent accidental movement thereof. Such vehicles typically are parked adjacent to a dock or other fixed structure during loading or unloading operations, and should the vehicles roll away from the dock, damage may occur to the vehicles or adjacent vehicles, and injuries may occur to workers nearby. Wheel chocks have been used for preventing such movement, but they do not afford adequate reliability for many applications in that they may slip on wet, iced, or greased surfaces, and they are subject to being misplaced or stolen.